【作者】 代快；

【导师】 蔡典雄；

【作者基本信息】 中国农业科学院 ， 农业水资源利用， 2012， 博士

【摘要】 华北平原生产的粮食超过了我国粮食总量的20%，以冬小麦/夏玉米轮作为主要种植模式，然而，为了追求高产，冬小麦/夏玉米轮作系统水肥投入量过高现象十分普遍，导致水肥利用率低下，同时造成环境污染，加剧水资源短缺，因此，研究不同水肥条件下冬小麦/夏玉米轮作模式中冬小麦和夏玉米水氮利用特征及产量，探索一种水肥资源高效利用且高产的优化管理模式，对保障我国粮食安全和农业可持续发展具有十分重要的意义。为研究华北平原不同水肥条件下冬小麦/夏玉米轮作模式中冬小麦和夏玉米水氮利用特征及产量，于2007－2010年在河北辛集马庄试验站布置了冬小麦和夏玉米田间小区试验和15N示踪的微区试验。冬小麦试验设置3个灌水水平：传统3次灌水（I3）；2次灌水（I2）；1次灌水（I1），每个灌水水平下设置5个施肥处理：完全无肥（CK），施磷钾肥（N0），在N0基础上施氮150（N150）、210（N210）及270kg N ha^-1（N270，传统施氮处理）。夏玉米试验设2个灌水水平，传统2次灌水（I2）条件下设置6个施肥处理：完全无肥（CK），施磷钾肥（N0），在相同磷钾肥（N0）基础上增施氮肥90（N90）、180（N180）及270kg N ha^-1（N270，传统施氮处理）及1次性施氮180kg N ha^-1（N180y），其他氮肥均分2次施用。在1次灌溉（I1）条件下，设置3个施肥处理；完全无肥（CK），施磷钾肥（N0），1次性施氮180kg N ha^-1（N180y）。15N微区试验选取小区试验中的施氮处理并分底肥和追肥分别进行示踪。主要结论概括如下：（1）探明了不同水肥条件下冬小麦/夏玉米农田氮肥去向：15N标记肥料氮为冬小麦（第1季）吸收量、土壤残留量及其他损失量分别为63.2～126.2、54.9～74.5、20.3～81.3kg N ha^-1，均随施氮量增加而显著增加。减施氮肥22%（N210）显著降低氮肥残留17.0%和其他损失37.8%，I2处理与I3处理氮肥残留量无显著差异。第2季夏玉米和第3季冬小麦吸收第1季冬小麦残留氮量分别为8.4～22.1、3.8～7.2kg N ha^-1。15N标记氮肥为夏玉米（第1季）吸收量、土壤残留量及其他损失量分别为43.4～104.8、44.0～137.3、2.6～27.9kg N ha^-1，均随施氮量增加而显著增加。减施氮肥33%（N180）显著降低氮肥残留35.0%和其他损失41.6%。第2季冬小麦和第3季夏玉米吸收残留氮量分别为6.7～18.7、2.0～5.7kg N ha^-1。（2）探明了不同水肥条件下冬小麦/夏玉米氮素利用特征：冬小麦拔节期、灌浆期和成熟期氮肥回收利用率分别为4.8%～32.5%、20.5%～59.9%和21.8%～44.2%。3个生育期氮肥回收利用率均随灌水次数增加而显著增加，I2处理成熟期平均氮肥回收利用率为32.0%，较I3处理（36.4%）显著降低12.1%，其他时期I2处理与I3处理无显著差异。氮肥仅对成熟期氮肥回收利用率影响显著，N210（34.8%）较N270（28.1%）显著提高23.8%。夏玉米大喇叭口期、吐丝期及成熟期氮肥回收利用率分别为3.9%～40.5%，5.1%～40.6%，3.8～48.0%。2次灌水条件下，相比传统施氮（N270），减量施氮33%（N180）对氮肥回收利用率无显著影响。施氮180kg N ha^-1，分2次施肥（I2N180）较1次施肥（I2N180y）显著提高大喇叭口期氮肥回收利用率，对其他时期无显著影响。灌水对3个时期氮肥回收利用率无显著影响。（3）探明了不同水肥条件下冬小麦/夏玉米水分利用效率：不同生育期冬小麦水分利用效率大小为：拔节期－灌浆期>灌浆期－成熟期>播种－拔节期。施氮量在210kg N ha^-1以下时，冬小麦籽粒水分利用效率及总生物量水分利用效率随着施氮量增加而显著增加，在210kg N ha^-1以上增加氮肥，则无显著变化。相比传统灌水I3，I2处理显著提高籽粒水分利用效率及总生物量水分利用效率。不同生育阶段夏玉米生物量水分利用效率大小为：吐丝期－成熟期>大喇叭口期－吐丝期>苗期－大喇叭口期>播种－苗期。施氮量显著影响夏玉米籽粒水分利用效率，I2N180与I2N270处理间差异不显著。（4）明确了不同水肥条件下冬小麦/夏玉米经济产量：不同水肥条件下冬小麦籽粒产量为3267～8789kg ha^-1，相对传统施氮270kg N ha^-1，减氮22%（N210）冬小麦产量提高约0.4%，平均达7847kg ha^-1。相对传统灌水I3，I2处理对产量影响不显著。不同水肥处理夏玉米籽粒产量为5122～9787kg ha^-1，减施氮肥33%处理（I2N180）夏玉米籽粒产量平均可达9201kg ha^-1，较传统水肥管理（I2N270）降低2.4%，无显著差异。（5）初步明确了冬小麦/夏玉米轮作条件下冬小麦和夏玉米优化管理方式及其经济效益：冬小麦和夏玉米优化管理方式分别为I2N210和I2N180，优化水氮条件下冬小麦和夏玉米净收入分别为7887、13113元ha^-1year-1，分别较传统水氮处理提高14.7%、0.03%。总净收入为21000元ha^-1year-1，较传统管理提高5.1%。综上所述，本文探明了不同水氮管理条件下冬小麦/夏玉米轮作模式中冬小麦和夏玉米产量和水氮利用特征，得到冬小麦和夏玉米优化管理方式分别为I2N210和I2N180，这种管理组合不仅提高水氮利用率，增产增收，同时较传统管理节水20%，节省氮肥28%，为华北平原冬小麦/夏玉米轮作农田水肥管理优化提供参考。更多还原

【Abstract】 The North China Plain （NCP） produces over20%of the national food-grain，with a dominant croppingsystem of winter wheat （Triticum aestivum L.） and summer maize （Zea mays L.） grown in rotation.However, in the pursuit of high yield, the overuse of nitrogen and water in winter wheat and summermaize rotation system （WW-SM） was very common, which had already led to low nitrogen and wateruse efficiency, meanwhile, exacerbated the water scarcity and environment pollution. It is imperative forfood security and sustainable agriculture to search on water and N use as well as the relevant grain yieldin WW-SM and then find an optimal water and nitrogen measures （OWNM）, under which water and Nuse efficiency were increased, while high crop yields obtained and the harm to environment byfertilization was diminished.In order to elucidate water and N use efficiency and crop yields under OWNM measures in WW-SM inNCP, field plot trials combined with micro-plot experiment with15N tracing from2007to2010werecarried out in Mazhuang Experimental Station in Xinji of Hebei province. The experiment design was asfollow: for winter wheat,3irrigation treatments were included: irrigation3times as conventional （I3）,2times irrigation with33%of water saved （I2）, and irrigation once with67%of water saved （I1）. Undereach irrigation condition,5fertilization levels were designed as: no fertilization （CK）,0（N0）,150（N150）,210（N210）,270（N270, the conventional level） kg N ha^-1with same amount of phosphorus （P）and potassium （K）, respectively. For summer maize, under the condition of irrigation twice（I2）,6fertilization treatments were included: no fertilization（CK）,0（N0）,90（N90）,180（N180）, and270（N270）kg N ha^-1with the same amount of P and K, and one treatment of180kg N ha^-1applied once （N180y）,N fertilizer of other treatments applied twice. And under the condition of irrigation once （I1）, there were3fertilization treatments such as: no fertilization （CK）, only P and K fertilizer （N0） and180kg N ha^-1fertilizer applied once （N180y）. Micro-plot experiment design was the same as the nitrogen fertilizationtreatments in the field plot, which was divided into2treatments of basal15N-urea labeled, with15N-ureatopdressed and labeled. Research mainly on the N absorption regularity, N residual in soil profile, grainyield, water and N use efficiency under OWNM measures in winter wheat and summer maize rotationsystem in NCP. The main results are as follows:（1） The fates of15N labeled urea in winter wheat and summer maize under different N rates andirrigations have been made clear. The urea-15N fates including N uptake by wheat plant (63.2¹26.2kgN ha^-1), soil residual N (54.9⁷4.5kg N ha^-1) and the unaccounted N losses (20.3⁸1.3kg N ha^-1)significantly increased as the fertilizer N rose. While the residual N and unaccounted N losses werenotably decreased by17.0%and37.8%, respectively, under N210（reducing22%of N）, compared tothat of N270. And there were no significant differences between treatment I2and I3. In addition, thelabeled residual-15N absorbed by the second and the third successive crops were8.4²2.1、3.8⁷.2kg Nha^-1, respectively. The urea-15N fates including N uptake by maize plant (43.4¹04.8kg N ha^-1), soilresidual N (44.0¹37.3kg N ha^-1) and the unaccounted N losses (2.6²7.9kg N ha^-1) significantly increased as the fertilizer N rose. In addition to the N recovered in the first maize crop, a further of6.7¹8.7kg N ha^-1was absorbed by the following wheat. An additional of2.0⁵.7kg N ha^-1wasabsorbed by the second maize crop grown after the wheat.（2） The nitrogen use efficiency in winter wheat and summer maize under different N rates andirrigations has been verified. The nitrogen recovery efficiency （RE） were ranged from4.8%to32.5%,from20.5%to59.9%and from21.8%to44.2%for elongation stage, grain filling stage and maturitystage of wheat season, respectively, all of which were enhanced as irrigation times added. And the REunder I2（33%of water saved） was32.0%in maturity stage, significantly down by12.1%, incomparison with that of conventional irrigation treatment （I3）. However, nitrogen only had a significanteffect on RE in maturity stage, and RE in maturity stage of N210（34.8%） were23.8%higher than thatof N270（28.1%）. The RE of maize were3.9%⁴0.5%,5.1%⁴0.6%,3.8⁴8.0%for spike formulationstage, silk stage and maturity stage, respectively. Under the condition of I2, reducing33%of N （I2N210）had no significant affect on RE in the3growing stages, when compared to those under conventional Nrate （I2N270）. Meanwhile, at the N rate of180kg N ha^-1, spilt applications of fertilizer N （I2N180）significantly increased RE in spike formulation stage, compared with applied fertilizer N once beforeseeding （I2N180y）. However, irrigations did not significant affect RE in the3growing stages.（3） Gotten a further clarification of water use efficiency （WUE） based on biomass and grain yield（WUEgrain） in winter wheat and summer maize under different N rates and irrigation. The water useefficiency based on wheat biomass in different growing stages ranked as: elongation to grain fillingstage>grain filling to maturity>seeding to elongation. And the WUE based on whole biomass andWUEgrain were significantly increased as the fertilizer N increased as the fertilizer N less than210kgN ha^-1, while there were no significant increase when the fertilizer N over210kg N ha^-1. The WUEgrainand WUE based on whole biomass of I2were significantly increased, when compared to those of I3.For maize, the WUE based on biomass in4growing periods ranked as: silk stage to maturity>spikeformulation stage to silk stage>seedling stage to spike formulation stage>sowing to seedling stage. Nrates had a significant effect on WUEgrain, however, there were no significant differences betweenI2N180and I2N270.（4） The grain yields of winter wheat and summer maize under different N rates and irrigations weredefinite. The wheat grain yields across treatments ranged from3267to8789kg ha^-1, with the meanreaching7847kg ha^-1under the condition of reducing22%of fertilizer N （N210）,0.4%higher （P>0.05）compared to that of N270(7816kg ha^-1). Meanwhile, the grain yield was not significantly decreasedunder condition of I2, in comparison with that under I3. For maize, the grain yield across treatmentsranged from5122to9787kg ha^-1. By reducing33%of fertilizer N （I2N180）, the mean grain yieldreached to9201kg ha^-1,2.4%less （P<0.05） than that of I2N270（P>0.05）.（5） Gained a preliminary idea of the optimal water and nitrogen measures （OWNM） and their economicbenefits. The optimal measures were I2N210and I2N180for winter wheat and summer maize, underwhich the net benefits were7887and13113yuan ha^-1year-1,14.7%and0.03%higher than those underconventional measures, respectively. The total income was increased by5.1%under the OWNM (21000 yuan ha^-1year-1) as compare to conventional measures.In conclusion, the water and nitrogen use of winter wheat and summer maize were made clear inWW-SM cropping system under different N rates and irrigations, suggesting that the combination ofI2N210for wheat and I2N180for maize was the optimal measure for WW-SM cropping system, underwhich higher grain yields and higher net income kept, as well as enhanced water and nitrogen useefficiency gained, moreover,20%of water and28%of nitrogen were saved. Therefore, it provided apowerful reference for the soil water and N management in winter wheat and summer maize rotationsystem in NCP.更多还原